Thank you! I tried this version and added the section to my personal.ini file but the cover image doesn't show up in Calibre nor on my Kindle, am I doing something wrong? The Generate Cover plugin is not needed, right?

EDIT: Nevermind, got it to work.
EDIT2: Not really, the image is now the first page in the epub, but is not shown as the cover-image in Calibre or on the Kindle (after and before conversion to MOBI).